Plugging contact



July 10, 1934. H. E. cox ET AL 1,966,234

PLUGGING CONTACT Filed Feb. 5, 1952 Inventors; 0 Horold E. Cox,

Momcus ClHu'nbev, Frederick A.Tuck,

Their Attorneu.

Patented m W934 PLUGGING CONTACT lli'arold Ernest Cox,

lnman Hunter,

London, Marcus Charles Teddington,

and Frederick Alfred Tuck, Kenton,,England, assignors to Gengral Electric Compa Yer Application February 3,

ny, a corporation of New 1932, Serial No. 590,730

lln Great Britain February 18, 1931 3 Claims.- (Cl. 173-363) The present invention relates to electric plug! ging contacts particularly, although not exclusively, adapted for use in electric switchgear where disengageable contact is required to be 5 efiected between stationary and movable parts of a switchgear. In particular, the invention is concerned with plugging contacts, usually known as self-aligning contacts, in which the contact making portion of one of the contacts is movable with respect to its support. This effect has previously been achieved by flexibly mounting one of the co-operating contacts in order that any slight degree of misalignment in the co-operating switchgear portions may be compensated for in the co-operating plugging contacts.

The invention consists in interconnecting cooperating contacts through the intermediary of a contact-making connector which is attached to and is adapted to have a limited degree of universal movement with respect to one of the contacts.

In carrying the invention into efiect, the universal movement is preferably provided by making the (co-operating contact surfaces of the contact-making connector and the plugging contact member of cylindrical and spherical or part spherical shape, and in making either the contact making connector or a part thereof or the plugging contact of resilient construction in order to ensure the proper contact pressure between the contact making surfaces. It will be seen that with co-operating spherical and cylindrical surfaces a substantial line contact is produced and it has been found important to make the contact pressure of considerable value in order to reduce the resistance as far as possible, since the greater the contact pressure the less the electrical resistance at the junction.

The desired contact pressure may be attained by forming one of the co-operating parts of the connector and plugging contact in the form of segments pressed outwardly or inwardly into contact with the co-operating surfaces by resilient means. Springs are preferably used for 5 this purpose, although the use of rubber or like resilient substance is visualized.

Preferably the universal movement is provided at both contact surfaces of the contact-making connector with the co-operating plugging contacts, and in accordance with one construction in which co-operating spherical and cylindrical surfaces are used, both plugging contacts comprise sockets which are engaged by spherical contact surfaces provided at opposite ends of the connector, one end of the connector being anchored within one of the socket contacts. In this construction, the resilient contact surfaces are provided on the connector by forming the connector in a number of segments held together by rings at either ends of the connector which engage circumferential slots in the segments, or by ment, the contact surfaces being preferably brazed to the segments. The use of silver for the contact surface is to be preferred to copper, for example, on account of its oxide being of reater conductivity than that of copper.

The contact making connector is anchored to one of the socket contacts by means of a pin passing through the opposite segments and projecting to engage recesses in the surrounding contact, the recesses or the apertures in the segments being of larger diameter than the pin in order to permit of the limited universal movement of the connector with respect to the contact. The inter-engaging edges of the free end of the connector and of the co-operating plugging contact are preferably chamfered to assist in the engagement of the contacts. The contacts may be suitably supported in hollow insulators attached to the co-operating portions of the switchgear in the usual manner, the insulators preferably overlapping for reasons well known to those versed in the art.

Our invention will be more fully set forth in the following description referring to the accompanying drawing, andthe features of novelty which characterize our invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Referring to the drawing, Fig. l is a longitudinal view, partly in section, of a preferred arrangement of coasting contacts embodying the present invention as applied for example to switchgear of the draw-out type, and Fig. 2 is an enlarged transverse sectional view taken along the line 2-2 of Fig. 1.

Referring more particularly to the drawing,

there are shown in Fig. 1 co-operating socket members forming contacts designated 2 and 8, adapted to be interconnected by means of the intermediate contact-making connector 1. In the drawing the two contacts are shown in the interconnected position. The contacts 2 and 8 are enclosed respectively by bushing insulators 4 and 3, and since contact 2 in the present instance is intended for connection to the stationary or busbar portion of a switchgear, the insulator 4 projects some distance beyond the contact 2 and protects it from accidental external contact when the removable portion of the gear is withdrawn. This is a well-known feature of draw-out switchgear and forms no part of the present invention.

The socket contact 2 is tapered externally as shown at 5 and is held within a corerspondingly tapered portion ofthe supporting member 6 by the bolt 7. The socket contact 8 is attached to the movable portion of the gear in a manner similar to that described in connection with contact 2. The contact making connector 1 consists of a plurality of longitudinally disposed segments 9 of which four are used in the arrangement illustrated. These segments, as best illus trated by Fig. 2, are held together as regards unlimited outward movement by restraining means as end rings 10 which co-operate with channels formed in the segments. Opposite pairs of segments are pressed outwardly against the rings 10 by resilient means as internal springs 11, which are correspondingly arranged in pairs, and which seat in recesses formed for this purpose in the segments. The connector 1 is attached through a lost motion connection to the socket contact 8 by means of the pin 12 which passes through the centre of left-hand spring 11 and projects into transverse holes drilled in the contact 8, the pin 12 being screw-threaded at its lower end and the hole in the contact 8 being similarly threaded to receive the pin 12. The bore of the holes through which the pin 12 passes in the segments 9 is of somewhat larger diameter than that of the pin 12, as indicated in the drawing, so as to allow the contact segments to have a limited universal movement with respect to the pin. Alternatively, the holes in the contact 8 might be made of larger diameter than that of the pin which would then be secured by screwing it to one of the segments through which it passes. The segments are provided externally with spherical contact surfaces 13 which co-operate with corresponding inserts 14 on the socket contact 8 and on the socket contact 2. As previously pointed out, the contact surfaces 13 may be formed by arcuate portions which are preferably brazed to the segments. These contact surfaces and inserts are preferably made of silver, for the reason above stated.

It will be seen that owing to the manner of supporting the connector 1 upon the pin 12, the connector is allowed a limited degree of universal I movement with respect to the socket contact 8,

while, at the same time owing to the internal springs 11 and spherical contact surfaces 13 adequate contact is maintained between the segments 9 and the socket contact 8. Furthermore, any lack of alignment between the contacts 2 and 8 still enables adequate connection to be maintained between those contacts by virtue of the spherical contact surfaces on the connector. It will be observed that the outer end of the contact 2 is bevelled at 15 to assist the tapered end of connector 1 to enter the contact 2 if they are not in alignment.

It has been found that the line contact produced between the spherical contact surfaces and the inserts 14 in conjunction with the high contact pressure produced by the springs 11 provides low contact resistance between the contacts.

It is evident that many modifications may be made to the arrangement shown in the drawing while still obtaining the desired universal movement. For example, the resilient contact surfaces may be provided on the socket contacts by making the socket contacts in the form of segments which are urged together by means of garter springs surrounding the sockets. Alternatively, the spherical contact surfaces may be provided on plug contacts and the connector may be of cylindrical form, and in this case the segmental resilient construction may be provided either, on the connector or on the co-operating plugs. A further arrangement is possible in which co-operating plug and socket contacts are engaged by an intermediate connector one end of which provides the spherical contact surface for engaging the socket, while the other end has a cylindrical contact surface engaging a plug with a'spherical contact surface. In such an arrangement, the segmental construction of resilient contact would prefrably be used on the plug and socket contact members.

In a modification, when the universal movement is permitted only between one end of'the contact making connector and the co-operating plug or socket contact, the connector is then allowed freedom of movement in one plane in its connection to the plug and socket to which it is attached. In this case the misalignment of the co-operating plugging contact in the direction in which freedom of movement is not allowed to the connector is provided for by allowing the cooperating plugging contact to engage the connector at different parts of the contact surface of the connector.

It should be understood that our invention is not limited to specific details of construction and arrangementthereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the spirit of our invention.

What we claim as new and desire to secure by Letters Patent of the United States, is:

1. An electrical connection of the plug and socket type comprising a pair of conducting socket members mounted for relative movement, an intermediate connector for said socket members, a, pin mounted transversely of one of said socket members for securing one end of said connector to said member, said pin extending through an enlarged bore in said connector so that a limited degree of universal movement of the free end oi said connector is permitted.

2. An electrical connection or" the plug and socket type comprising a pair of relatively movable conducting socket members and an intermediate connector for said members comprising a plurality of relatively movable segments, resilient means normally biasing said segments outwardly into engagement with said socket members in the connected position, restraining means at the opposite ends of said connector for limiting the outward movement of said segments, and a pin mounted in and transversely of one of said socket members provided with a lost motion connection with said segments at one end of said connector arranged so that the opposite end of said connector has a limited degree of universal movement.

3. An electrical connection of the plug and socket type comprising a pair of relatively movable conducting socket members and an intermediate connector for said members comprising a plurality of relatively movable longitudinally disposed segments, resilient means biasing said segments outwardly into engagement with said socket members in the connected position, a pair of rings at opposite ends of said connector for 

